Write-Off Categories Explained: Cat A, B, S and N

An insurance write-off sounds terminal, but a large share of written-off cars are repaired and sold on entirely legally. The category letter tells you which kind you're looking at. Cat A and Cat B cars are damaged beyond any return to the road; Cat S and Cat N cars can be repaired, re-insured and driven for years, usually bought at a healthy discount.

What every category shares is permanence. The marker follows the car for the rest of its life, and it lives on an insurance-industry register that free checks can't see, which is exactly how written-off cars end up sold as clean ones. This guide explains each category, the older Cat C and Cat D letters you'll still meet, what a marker does to price, insurance and finance, and how to check before you commit.

What an insurance write-off actually is

A car is written off when an insurer decides that repairing it would cost more than it's worth, or that the damage is so severe no repair could make it safe. The insurer pays the owner the car's market value, takes ownership of the vehicle and assigns a salvage category describing the damage. That category is recorded against the car on the Motor Insurance Anti-Fraud and Theft Register (MIAFTR), the insurance industry's shared database, where it stays permanently, surviving repairs, resales and changes of keeper.

The current four categories (A, B, S and N) arrived in October 2017. The older system graded write-offs mainly by repair cost; the new one grades them by the nature of the damage, drawing the important line at the car's structure. The change recognised a modern reality: cars full of sensors, aluminium panels and expensive light clusters are routinely written off over damage that never went near the chassis.

Worth knowing early: "write-off" doesn't always mean "crash". Flood damage, vandalism and theft recovery after a claim has been paid can all put a marker on an otherwise ordinary car.

Cat A: scrap only

Cat A is the most severe grade. The damage is so extensive (typically burnt-out, crushed or fully submerged vehicles) that nothing can be salvaged. The entire car must be destroyed, individual parts included; none of it may be resold or reused.

A Cat A car can never legally return to the road. If you're ever offered a "repaired Cat A", you're looking at fraud: walk away and keep your money. There is no price at which it becomes a deal.

Cat B: break for parts

Cat B means the body shell is beyond saving and must be crushed, but undamaged components (engine, gearbox, seats, doors, electronics) may be removed and sold as spares. Salvage yards buy Cat B cars for exactly this purpose, and there's nothing wrong with fitting a used engine that came from one.

The car itself, though, is in the same position as a Cat A: it must never be repaired and driven again. A "rebuilt Cat B" offered for sale is not road-legal however tidy it looks, and Cat B shells occasionally resurface wearing another vehicle's identity, one reason checking the VIN against the V5C matters on any used car.

Cat S: structural damage, repairable

The S stands for structural. Something load-bearing or safety-critical (chassis rails, subframe, sills, pillars, floor pan or a crumple zone) was damaged, and the insurer judged repair uneconomic. Unlike A and B, a Cat S car can legally return to the road once it has been properly repaired.

Two things follow from the word "structural". First, repair quality is everything. Modern bodies are engineered to deform predictably in a crash, and a structural repair done badly can behave unpredictably in the next one. No mandatory engineering inspection stands between a Cat S repair and the road (the system leans on the competence of whoever did the work), so an independent inspection by someone who knows body repair is money well spent.

Second, there's paperwork. A Cat S must be re-registered with the DVLA before it goes back into use, and the write-off is recorded against the vehicle with a replacement V5C issued. A seller who can't produce the V5C, or whose story doesn't line up with its dates, is a seller to leave behind.

Priced properly (expect 20–40% below a clean equivalent), a well-repaired Cat S can be a rational buy. Insist on the repair invoice, photos of the work in progress if they exist, and that independent inspection before you commit.

Cat N: non-structural damage, repairable

The N stands for non-structural. The chassis and crumple zones are sound; the damage sat in panels, bumpers, lights, interior trim, electrics or airbags. Many Cat N write-offs were never dangerous at all: on an older car, a bumper, a headlight cluster and a deployed airbag can comfortably exceed the car's value, and the insurer writes it off on arithmetic alone.

That makes Cat N the most buyable category, but not a blind buy. Airbag and electrical repairs are where corners get cut: check that the airbag warning light comes on with the ignition and goes out a few seconds later; a light that never appears at all may have been disabled rather than repaired. There's no DVLA re-registration requirement for Cat N, so the paperwork looks completely ordinary; the marker only surfaces on a paid history check.

Discounts run around 10–25% against a clean car. With documented repairs and a proper inspection, a Cat N can be one of the best value-for-money routes into an otherwise expensive model.

The legacy letters: Cat C and Cat D

Cars written off before October 2017 keep the letters they were given at the time, so Cat C and Cat D still show up on older vehicles; existing markers were never converted to the new system.

The mapping is rough rather than exact, because the old system graded by repair economics, not damage location. Cat C meant repairs would have cost more than the car was worth; Cat D meant repairs were cheaper than the value but the insurer still chose not to fix it. Some Cat C cars never had structural damage; others had plenty. For buying purposes, treat a Cat C like a Cat S and a Cat D like a Cat N: same questions, same inspection, same discount expectations.

Cat S vs Cat N side by side

The one-line version: Cat N tells you what got broken; Cat S tells you the car's bones were involved. Both can be fine buys; Cat S simply demands a higher standard of proof.

Buying a written-off car

A written-off car is only worth buying with the facts on the table. A sensible order of attack:

1. Confirm the category before negotiating. A paid history check returns the MIAFTR record: the category and the date. Without it you're relying entirely on the seller's honesty.
2. Ask the question in writing. Dealers must disclose write-off status under the Consumer Rights Act 2015, and a private seller who lies when asked directly is committing misrepresentation. An email trail keeps everyone honest.
3. Get an insurance quote before you offer. If mainstream insurers won't quote at all, that's information.
4. Match the inspection to the category. For Cat S, pay a body-repair specialist to assess the structural work. For Cat N, focus on electrics, airbags and the quality of the visible repair.
5. Demand the repair paperwork. A proper bodyshop invoice with a parts list beats any verbal assurance; photos taken during the repair are better still.
6. Test drive at length. Wandering steering, a car that tracks crooked on a straight road, brake pull and odd noises over bumps are the classic signs of a poor structural repair.
7. Negotiate against the marker. A written-off car priced 5–10% below clean market isn't discounted enough: the marker follows the car, and so should the discount.

Two traps sit outside the categories entirely. Unrecorded damage (an owner who paid for crash repairs privately, without a claim) leaves no marker on any database, which is why an inspection matters even when the history check is clean. And cloning cuts the other way: a written-off car's identity can be transplanted onto a stolen one, so confirm every VIN on the car matches the V5C before you rely on any paperwork at all.

Insurance, finance and resale with a marker

Insurance. A write-off marker is a material fact: declare it every time you insure the car, or you risk the policy being voided exactly when you need it. Some insurers decline written-off cars outright; most of the rest apply a loading, commonly in the 10–20% region; specialist brokers handle them as routine business. Quote before you buy the car, not after.

Finance. Mainstream HP and PCP lenders usually refuse to lend against a car with a write-off marker, whatever the category. That bites twice: once if you need finance to buy it, and again when you sell, because your future buyer probably can't finance it either, which shrinks your market to cash buyers. If the car also has money still owing on it, that's a separate danger; our guide to outstanding finance covers it.

Resale. The discount you buy at is roughly the discount you'll sell at: the marker doesn't fade, so a Cat S bought 30% under market will sell around 30% under market too. Two practical consequences: the longer you keep the car, the less the marker costs you per year of ownership, and every scrap of repair documentation you keep adds to what the next buyer will pay.

How to check if a car is a write-off

Here's where we're straight about our own check. Write-off markers live on MIAFTR, which is owned and fed by the insurance industry; it is not part of the DVLA's public data, so our free car check cannot show write-off status, and neither can any other free service. Only paid, HPI-style checks license that data. Expect to pay roughly £10–£20, and see our guide to what an HPI check includes for how to pick one.

The free check still earns its place in the process. Run the registration first and you'll confirm the car's identity and spec, its tax and MOT position, and its full MOT history with mileage readings, where a long gap in tests or a sudden mileage anomaly can hint at a hard life, even though a clean MOT record is never proof there's no marker. Free first to filter, paid before you commit: that order costs nothing extra and catches nearly everything.

The bottom line

Cat A and Cat B are absolute: those cars are scrap and spare parts, never transport again. Cat S and Cat N (and their older cousins C and D) are judgement calls that come down to three things: proof of a competent repair, an insurance quote in hand, and a discount that genuinely reflects the marker. Get all three and a written-off car can be honest value; miss any and you're carrying someone else's risk at your expense. Check before you fall for the car. And for everything else worth doing before the money moves, our used car buying checklist has the full list.